Method and agent for drying gases



Patented a.. 4, 1927.

WIIHELM M'ULIIEB, OF BITTERFELD, GERMANY, ASSIGNOB TO THE FIRE I. G. FARIBEN- INDUSTRIE AKTIENGESELLSOHAFT, OF FRANKFORT-ON -'IHE-MA1N, GERMANY.

METHOD AND AGENT FOR DRYING GASES.

Ho Drawing. Application filed March 80, 1927, Serial No. 179,718, and in Germany June I, 1926.

This invention relates to the method'of drying air and other gases b means of phos-' phorus. pentoxid. The we] -known method of drying gases by means of solid phosphorus pentoxid is objectionable from an industrlal point of view, owing to the fact that this substance melts away at its surface when absorbing water, whereby the adjacent layers are coated with a hardcrust, and a considerable part of the phosphorus pentoxid becomes inaccessible to moist air and therefore inoperative.

Now I have found that gases can be dried with utmost facility by employing phosphorus pentoxid, not in solid form but in form of a solution in phosphoric acid. Air, for instance, is dried by such a solution already after short contact therewith. Whereas, for instance, an aqueous phosphoric acid containing 80% of phosphoric acid absorbs only 67% of the water content within a certain time of contact, under the same conditions the drying effect of undiluted phosphoric acid amounts to 90%, and of a solution of 35 12% of phosphorus pentoxid in undiluted 'phosphorlc acid to 100%. The vapor tension of the water in these phosphorus pentoxid solutions is so extraordinarily small other gases which com rises treatmg and to such a degree inde endent of the temperature that it is ossi Is to work at elevated temperatures or instance, at 80 (1.; therefore the method may be employed if the gases under treatment are hot.

My improved method has special advanta es, for instance, in connection with the manu acture of high-grade phosphoric acid by combustion of hos horus or gas mixtures containing F osphbrus, by means of dry air, as part 0 the phosphorus pentoxid obtained by this process may be employed itself as drying agent in the above indicated form. Preferably the phos horic acid containing phosphorus pentoxid is used for drying purposes until, by absorbing water-from the air to be dried, a 100% phosphoric acid is formed.

I claim 1. The improved method of drying air fir t e gases with a solution ofp osphorus pentoxid in anhydrous phosphoric acid.

2. An agent for drying air or other ases, consisting of anhydrous phosphoric acid in which phosphorus pentoxid is dissolved.

In testimony whereof I afiix my signature. 

